The present Invention relates to an apparatus for the thermal treatment of substrates, especially semi-conductor wafers, and includes a reaction chamber and a compensation element that surrounds the outer periphery of the substrate and is spaced therefrom. The present invention also relates to a method for the thermal treatment of substrates, especially semiconductor wafers, in a reaction chamber having a compensation element that surrounds the outer periphery of the substrate and is spaced therefrom.
A method and an apparatus of this type are described in DE 36 27 598 C. A compensation ring is provided about a wafer In a reaction chamber of the apparatus. During the thermal treatment of the wafer, the compensation ring prevents edge effects. With this ring, for example a more rapid heating up at the rim than at the inner region of the wafer during a heating-up phase, and a more rapid cooling off during a cooling-off phase, are avoided. Due to the compensation ring, temperature inhomogeneities within the wafer are thus eliminated or at least reduced. For a particularly good operation, the compensation ring is disposed essentially on the same plane as the wafer that is to be treated.
In the past, during the loading and unloading of the substrate that is to be handled, the compensation ring was grasped together with the substrate and introduced or withdrawn, since a handling device could freely grasp the wafer.
This common handling of wafer and compensation ring requires a complicated handling apparatus that in addition to a wafer-grasping apparatus must also have a compensation ring-grasping apparatus. Furthermore, due to the common handling there is an increased danger of damage to the compensation ring and/or to the wafer. U.S. Pat. No. 5,683,518, as well as JP 10-098 048, each disclose apparatus for the thermal treatment of substrates and have a reaction chamber and a compensation element, according to which during the thermal treatment the substrate rests upon the compensation element and is raised together with it in the reaction chamber. For loading and unloading, the substrates are placed upon posts that extend through the compensation element, with the respective compensation elements being completely lowered.
It is therefore an object of the present invention to provide a method and an apparatus for the thermal treatment of substrates that facilitate an introduction and withdrawal of the wafer into or out of the reaction chamber.
Proceeding from the initially mentioned apparatus, the stated objective is realized in that the compensation element is at least partially pivotable in the reaction chamber. By at least partially pivoting the compensation element in the reaction chamber, a direct access of a handling device to the wafer is possible, since the compensation element can be pivoted out of the access region of the handling device. In this connection, it is not absolutely necessary that the entire compensation element be pivoted; rather, it is sufficient to partially pivot the compensation element in order to enable free access to the wafer.
A pivot device is advantageously provided in the reaction chamber for the compensation ring or parts thereof, so that no such device has to be introduced from the outside.
Pursuant to one preferred specific embodiment of the invention, the pivot device is essentially spaced from the compensation element and is connected therewith by at least one connecting element. Spacing the pivot device from the compensation element ensures that the pivot device will exert no or only a slight thermal effect upon the compensation element.
The pivot device advantageously has a semi-circular member having an inner radius that is greater than the outer radius of the compensation element in order to influence the thermal treatment of the substrate as little as possible. For a simple construction of the pivot device, the free ends of the semi-circular member are mounted in the reaction chamber.
Pursuant to a further specific embodiment of the invention, the compensation element itself is pivotably mounted, resulting in a particularly straightforward pivotability.
Due to the typical shape of the substrates that are to be handled, the compensation element is preferably an annular or ring element. Pursuant to one specific embodiment, the compensation element comprises a plurality of segments in order to facilitate manufacture of the compensation element. This applies in particular for large substrates since the compensation element is typically made of the same material as the substrate and it is therefore difficult to manufacture the compensation element in the required size as one piece. The segments advantageously have angular segments of 60xc2x0 each. For smaller substrates, as well as for compensation elements that are not made of the same material as are the substrates that are to be handled, the compensation element is preferably a single piece.
Pursuant to one particularly preferred specific embodiment of the present invention, the pivot device can be controlled by movement of a door of the reaction chamber, and especially automatically by the opening or closing of the chamber door. By automatic pivoting together with the movement of the chamber door, there results a particularly straightforward actuation mechanism. The automatic pivoting furthermore ensures that when the chamber door is opened, access to the wafer is provided.
Proceeding from the initially described method, the stated objective is also inventively realized in that the compensation element is pivoted at least partially in the reaction chamber in order to facilitate the insertion and/or removal of the substrate. This again results in the advantage that the access to the substrate is provided and it can therefore be introduced and removed without obstruction.
The compensation element is advantageously automatically pivoted by opening or closing the door of the reaction chamber. This automatically ensures that access is provided to the substrate when the chamber door is opened.